net: manage napi add/del idempotence explicitly
To RCUify napi->dev_list we need to replace list_del_init() with list_del_rcu(). There is no _init() version for RCU for obvious reasons. Up until now netif_napi_del() was idempotent so to make sure it remains such add a bit which is set when NAPI is listed, and cleared when it removed. Since we don't expect multiple calls to netif_napi_add() to be correct, add a warning on that side. Now that napi_hash_add / napi_hash_del are only called by napi_add / del we can actually steal its bit. We just need to make sure hash node is initialized correctly. Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -355,7 +355,7 @@ enum {
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NAPI_STATE_MISSED, /* reschedule a napi */
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NAPI_STATE_DISABLE, /* Disable pending */
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NAPI_STATE_NPSVC, /* Netpoll - don't dequeue from poll_list */
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NAPI_STATE_HASHED, /* In NAPI hash (busy polling possible) */
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NAPI_STATE_LISTED, /* NAPI added to system lists */
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NAPI_STATE_NO_BUSY_POLL,/* Do not add in napi_hash, no busy polling */
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NAPI_STATE_IN_BUSY_POLL,/* sk_busy_loop() owns this NAPI */
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};
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@ -365,7 +365,7 @@ enum {
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NAPIF_STATE_MISSED = BIT(NAPI_STATE_MISSED),
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NAPIF_STATE_DISABLE = BIT(NAPI_STATE_DISABLE),
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NAPIF_STATE_NPSVC = BIT(NAPI_STATE_NPSVC),
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NAPIF_STATE_HASHED = BIT(NAPI_STATE_HASHED),
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NAPIF_STATE_LISTED = BIT(NAPI_STATE_LISTED),
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NAPIF_STATE_NO_BUSY_POLL = BIT(NAPI_STATE_NO_BUSY_POLL),
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NAPIF_STATE_IN_BUSY_POLL = BIT(NAPI_STATE_IN_BUSY_POLL),
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};
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@ -6533,8 +6533,7 @@ EXPORT_SYMBOL(napi_busy_loop);
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static void napi_hash_add(struct napi_struct *napi)
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{
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if (test_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state) ||
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test_and_set_bit(NAPI_STATE_HASHED, &napi->state))
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if (test_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state))
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return;
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spin_lock(&napi_hash_lock);
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@ -6559,8 +6558,7 @@ static void napi_hash_del(struct napi_struct *napi)
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{
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spin_lock(&napi_hash_lock);
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if (test_and_clear_bit(NAPI_STATE_HASHED, &napi->state))
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hlist_del_rcu(&napi->napi_hash_node);
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hlist_del_init_rcu(&napi->napi_hash_node);
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spin_unlock(&napi_hash_lock);
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}
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@ -6595,7 +6593,11 @@ static void init_gro_hash(struct napi_struct *napi)
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void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
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int (*poll)(struct napi_struct *, int), int weight)
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{
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if (WARN_ON(test_and_set_bit(NAPI_STATE_LISTED, &napi->state)))
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return;
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INIT_LIST_HEAD(&napi->poll_list);
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INIT_HLIST_NODE(&napi->napi_hash_node);
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hrtimer_init(&napi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);
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napi->timer.function = napi_watchdog;
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init_gro_hash(napi);
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@ -6650,6 +6652,9 @@ static void flush_gro_hash(struct napi_struct *napi)
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/* Must be called in process context */
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void __netif_napi_del(struct napi_struct *napi)
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{
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if (!test_and_clear_bit(NAPI_STATE_LISTED, &napi->state))
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return;
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napi_hash_del(napi);
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list_del_init(&napi->dev_list);
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napi_free_frags(napi);
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